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ion Room Temperature Megneto-Electric Effects in

Sr-Z Hexa-FerriteCarmine Vittoria, Northeastern University, DMR 1002543

• Outcome: Researchers at Northeastern university have created a room temperature magneto-electric material. Also, they have invented a novel technique to measure changes in permeability constant directly for the first time.

• Impact: It may be possible to electronic tune ferrite devices by the application of voltage only and do away with permanent magnets and current generators.

• Explanation: Magnetoelectric effects of Sr Z-type hexaferrite, Sr3Fe24Co2O41 , at room temperature have been measured. The E-field induced change in permeability was measured by applying a DC voltage or electric field across a slab of SrZ hexaferrite. In these types of measurements high resistivity is critical in order to reduce current flow in the hexaferrite. The resistivity of the SrZ hexaferrite was raised to 4.28x108

Ω-cm by annealing under oxygen pressure. The measurements indicate that indeed electric polarization and magnetization changes were induced by the application of magnetic and electric fields, respectively. The implications for room temperature microwave applications appear to be enormous, since there will be no need for magnetic tuning via permanent magnets, for example.